Calculate the sum of the series:
1+2+3+...+40+41+40+...+3+2+1.
Show answer & explanation
Correct answer: D
Explanation
Given:
Series = 1 + 2 + 3 + … + 40 + 41 + 40 + … + 3 + 2 + 1
Formula:
1 + 2 + 3 + … + n = n(n + 1)/2
1 + 2 + 3 + … + 40 = 40 × 41/2 = 820
Series = (1 to 40) + 41 + (40 to 1)
= 820 + 41 + 820 = 1681